Optical confinement is essential in order to increase the amount of photogeneration in a crystalline silicon (c-Si) solar cell. Fraunhofer examines the compatible options for wafers created using diamond wire sawing.
Leading up to the PV ModuleTech 2017 conference, less than 3 months away (Kuala Lumpur, 7-8 November 2017), this blog series explains why this dedicated two-day industry event has the potential to provide some key answers for EPCs, developers and asset owners, in terms of understanding the key metrics that underpin solar modules going forward, ultimately mitigating risks during site design and build-out, while optimizing overall return-on-investment for more than 20 years in the field.
READ PART ONE HERE
High-performance multicrystalline (HPM) silicon, achieved by nucleation on special seed layers at the crucible bottom, is now increasingly replacing conventional multicrystalline (mc) silicon, which is solidified on the standard silicon nitride coating. The HPM material is characterized by a very fine initial grain structure consisting of small, regularly shaped grains surrounded by a large number of random-angle grain boundaries. These grain structure properties, which differ significantly from those of conventional multicrystalline silicon, lead to a much lower dislocation content in the material, and therefore result in higher efficiencies of the silicon solar cells produced. This paper gives a rough overview of the worldwide R&D activities on HPM silicon in recent years, supplemented by several research results obtained at Fraunhofer IISB/THM. The focus is on the different seeding methods, the grain structure properties and the development of the grain and defect structure over the ingot height, as well as on the main challenges for further improvements in material quality and production costs.
A novel nanoscale pseudo-pit texture has been formed on the surface of a multicrystalline silicon (mc-Si) wafer by using a metal-catalysed chemical etching (MCCE) technique and an additional chemical treatment.
A desirable nanoscale inverted-pyramid texture was created by optimizing the recipe of the MCCE solution and using a proprietary in-house chemical post-treatment; the depth and width of the inverted pyramid was adjustable within a 100–900nm range. MCCE black mc-Si solar cells with an average efficiency of 18.90% have been fabricated on CSI’s industrial production line, equating to an efficiency gain of ~0.4%abs. at the cell level. A maximum cell efficiency of 19.31% was achieved.
Talesun has launched a new double glass photovoltaic panel with aluminum frame that has achieved TÜV certification. The ‘TWINKLE’ (TD660P) 60-cell multicrystalline panel uses the aluminum frame as the sealing point for the panel’s edges, the double glass modules are therefore weather-resistant and easier to install and transport.
Integrated PV module manufacturer REC Group has claimed that a pre-production batch of multicrystalline solar cells at its manufacturing plant in Singapore achieved a best conversion efficiency of 20.47% measured by an in-house tester with an external calibration cell.
Solar module manufacturer Hanwha Q CELLS has officially set a new world record in multicrystalline PV module efficiency, as the independent Fraunhofer ISE CalLab confirmed an efficiency rating of 19.5% in relation to the aperture area and a power output of 301 watts.